Striking the “right” balance between engaging in either familiar or brand-new research directions is one of the most defiant challenges for early career researchers. The former are crucial for building up momentum and expertise quickly in a newly minted laboratory, while the latter are critical for developing an independent voice in the field. An increasingly competitive funding landscape pushing researchers to propose new, original concepts while also showing preliminary results, further exacerbates this task. In this talk, I will outline our multi-year quest to understand the genesis of active sites in heterogeneous olefin metathesis catalysts. Surprisingly, even after decades of research, the nature of the active sites in industrial WO3/SiO2 and MoO3/SiO2 metathesis catalysts is poorly understood and remains a highly contested topic. This stands in stark contrast to our detailed knowledge of the Hérisson-Chauvin mechanism governing the Grubbs or Schrock metathesis catalysts. Indeed, studies using model catalysts support the notion that transition metal oxides likely also follow the Hérisson-Chauvin mechanism, but the understanding of the oxide to carbene conversion process remains ambiguous and has generated disparate results in the literature. We obtained unique mechanistic insights from extensive studies coupling rigorous kinetic measurements, in situ characterization results, and ab initio calculations on supported oxide catalysts. These data revealed a clear path to control active site speciation, fully reconciled traditionally incongruent reaction kinetics reported in the literature, and allowed us to implement strategies to universally promote metathesis rates. This exciting body of work was shaped by many adversities and failures, and it serves (at least to some extent) as an example of the benefits of persistence and patience when trying to find solutions to difficult problems during early years as an independent PI.

Universal promotion of heterogeneous olefin metathesis catalysts: Story about failure and perseverance during the early career research years

2019 Fall National Meeting

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